The present invention relates to a method to support catalyst compounds and/or improve catalyst activity and a polymerization process using these supported compounds to produce polyolefins. Preferably, one or more catalyst compounds are contacted with an aluminum alkyl and or an alumoxane in solution, and thereafter are contacted with a supported activator.
Advances in polymerization and catalysis have resulted in the capability to produce many new polymers having improved physical and chemical properties useful in a wide variety of superior products and applications. With the development of new catalysts the choice of polymerization (solution, slurry, high pressure or gas phase) for producing a particular polymer has been greatly expanded. Also, advances in polymerization technology have provided more efficient, highly productive and economically enhanced processes. The use of inorganic supports for catalysts has long been the standard practice for commercial gas- and slurry-phase polyolefin production. While in some cases, the interaction of the inorganic support with the catalytic metal may play a beneficial role in defining the catalytic properties of the system, a primary motive for use of inorganic supports is the morphological control they impart to the growing polymer particles. As a result, preferred methods for delivery of catalysts to commercial reactors involve the conveyance of the catalyst in some solid form, either as a dry powder or mineral oil slurry.
Though inorganic-supported catalysts, particularly silica-supported catalysts, have much to offer regarding simplicity of catalyst production and particle size control in commercial operation, the use of conventional supporting materials carry several disadvantages as well. First and foremost, many catalysts experience significant activity losses when they come in contact with silica supports. Several explanations have been provided for this observation and include irreversible catalyst decomposition by reaction with chemical functionality on the support and catalyst inhibition by Lewis basic coordination of surface functionality in competition with monomer coordination. Full-sandwich (metallocene) catalysts appear the least affected by interaction with support materials and moderate activity losses are suffered when the mode of catalyst delivery is changed from liquid to solid-supported. In contrast, half-sandwich (monocylopentadienyl) catalysts and non-metallocene catalysts can become completely inactive when exposed to silica materials and early strategies aimed toward commercialization of these catalysts focussed exclusively on solution delivery technologies.
Thus, there is a desire in the industry using this technology to reduce the complexity of the process, to improve the process operability, to increase product characteristics or to vary catalyst choices, i.e. by providing means to place half-sandwich (monocylopentadienyl) catalysts and non-metallocene catalysts on a silica support without losing catalytic ability. Thus, it would be advantageous to have a process that is capable of improving one or more of these industry needs.
This invention relates to a method to support one or more catalyst compounds comprising contacting the catalyst compounds with an aluminum alkyl or organoaluminum compound, and or an alumoxane in solution and thereafter contacting the combination with a supported activator. The aluminum alkyl may be represented by the formula Al(R)3, where each R group is independently a C1 to C40 alkyl group. The alumoxane may be any alumoxane or modified alumoxane as described in the activator section below. The supported activator is any activator as described below that has been deposited on, contacted with, vaporized with, bonded to, or incorporated within, adsorbed or absorbed in, or on, an inert particulate, a support or carrier. Support materials of the invention include inorganic or organic support materials, preferably a porous support material.